From: Rick DeNatale <rick.denatale@...>
Date: 2009-03-04T03:04:23+09:00
Subject: Re: expanding environment variable

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On Tue, Mar 3, 2009 at 11:30 AM, Gary Wright <gwtmp01@mac.com> wrote:

>
> On Mar 3, 2009, at 10:50 AM, Dominik Honnef wrote:
>
>> Or: s = "$DIR/test/$FILE".gsub(/\$(\w+)/) { ENV[$1] }
>>>
>> Probably depends on whether you like global variables or not. It is
>> definitely shorter/more readable and I actually didn't know if gsub
>> sets $1.
>>
>
> $1 isn't a true global variable.  It is a per-thread variable.  It
> still is a bit 'magic' for many people's tastes but it isn't as bad
> as a true global.
>

Actually its really a frame local variable. heres a bit of artificial code
which illustrates this:

def m1(string)
  string.scan(/(ab|ac)/) {|m|
    puts "in m1 $1 is #{$1}"
    result = m2($1)
    puts "result is #{result}, $1 is #{$1}"
    }
end

def m2(string)
  "z#{string}".scan(/(za)/) {|m|
    puts "in m2 $1 is #{$1}"
    $1
  }
end

m1("abcac") # => "abcac"
# >> in m1 $1 is ab
# >> in m2 $1 is za
# >> result is zab, $1 is ab
# >> in m1 $1 is ac
# >> in m2 $1 is za
# >> result is zac, $1 is ac


-- 
Rick DeNatale

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